Run pytest inside tox with coverage

.coveragerc

@@ -0,0 +1,34 @@
+[run]
+# measure 'branch' coverage in addition to 'statement' coverage
+# See: http://coverage.readthedocs.org/en/coverage-4.0.3/branch.html#branch
+branch = True
+
+# list of directories or packages to measure
+source = ufo2ft
+
+# these are treated as equivalent when combining data
+[paths]
+source =
+    Lib/ufo2ft
+    .tox/*/lib/python*/site-packages/ufo2ft
+    .tox/pypy*/site-packages/ufo2ft
+
+[report]
+# Regexes for lines to exclude from consideration
+exclude_lines =
+    # keywords to use in inline comments to skip coverage
+    pragma: no cover
+
+    # don't complain if tests don't hit defensive assertion code
+    raise AssertionError
+    raise NotImplementedError
+
+    # don't complain if non-runnable code isn't run
+    if 0:
+    if __name__ == .__main__.:
+
+# ignore source code that can’t be found
+ignore_errors = True
+
+# when running a summary report, show missing lines
+show_missing = True

.travis.yml

@@ -1,14 +1,17 @@
 sudo: false
 language: python
-python:
-  - "2.7"
-  - "3.6"
+matrix:
+  include:
+    - python: 2.7
+      env: TOXENV=py27-cov
+    - python: 3.6
+      env: TOXENV=py36-cov
 branches:
   only:
     - master
     - /^v\d+\.\d+.*$/
 
-install: pip install tox-travis
+install: pip install tox
 script: tox
 
 deploy:

tox.ini

@@ -1,9 +1,24 @@
 [tox]
-envlist = py27, py36
+envlist = py{27,36}-cov, htmlcov
 
 [testenv]
 deps =
+    cov: coverage
     pytest
     -rrequirements.txt
 commands =
-    py.test {posargs}
+    # run the test suite against the package installed inside tox env.
+    # We use parallel mode and then combine later so that coverage.py will take
+    # paths like .tox/py36/lib/python3.6/site-packages/fontTools and collapse
+    # them into Lib/fontTools.
+    cov: coverage run --parallel-mode -m pytest {posargs}
+    nocov: pytest {posargs}
+
+[testenv:htmlcov]
+basepython = python3.6
+deps =
+    coverage
+skip_install = true
+commands =
+    coverage combine
+    coverage html